Skip hoist control



July 10, 1945. 2,379,958

G. FOX

SKIP HOIST CONTROL Filed Dec. 11, 1942 12 Sheets-Sheet 1 ConneciedToConnecded To Left Skcp/Rlght Ski I Molar 2 Push Butfons L SUB RSUB 5t upand Rese t-Run R esls era Hols! 5 Hous 1 [H1 H l M l I J Control y 1Assembly N NTOR- a": i V I I I G 0211012 F 0 x I 5! la} 12 Sheets-Sheet3 S l a \QN \NN .I ll. llllllllllllllll II IIIIIPIII Ill ll'lll ||lQNNIIIIIIIIIIIJIIIIIlllllllll F NNI'I'IIIIIII I I'l-nlll'lulnllnll llL-l EN lllllllllllllllllllllllll ll lllllllllllllllllllilll ATE \\\N 5lull-llnlllll'l I'llllll'll ll'llllllllll ll'llllIl-nl IllllIl-ll I:

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1N VENT OR. Gar-don Fox @utsf 6' i fy? July 10, 1945. 6. FOX

SKI P HOIST CONTROL Filed Dec. 11, 1942 12 Sheets-Shut 6 INVENTOR.

Gard an F 0x I W July 10, 1945.

G. ox

SKIP HOIST CONTROL Filed Dec. 11. 1942 12 Sheets-Sheet '7 INVENTOR.Gordon Fax i fy July 10, 1945.

a. Fox 2,379,958

SKIP HOIST CONTROL Filed Dec. 11, 1942 12 Sheets-Sheet 11 ControlTransfer Switch Switch Motor 1 Hoist House Motori Stock House Motor 2S20 ck House Motor 2 Hoist House Two Motor NQ IA INVENTOR.

Gordon Fox BY July 10, 1945. 6. FOX 2,379,958

SKIP HOIST CONTROL Filed Dec. 11, 1942 12 Sheets-Sheet 12 ControlTransfer Switch-(Continued) otorI oiorI Two Motor 2 Moior C7351 SwitchHoist Stock Meier Stock Hoist House House House House a-b x 3"? *3 12-0x a-b x 22 H H be X X a-b x x 25 be x a-b x X 24 H- H be X X 0-1; x XLn-HM b-c x x a-b x x 26 b1: x X 0-!) x x 27 HH- c X X a-b x X 26 H -Hbe X X a-b x x PPM-A b-c x X signifies Circuii' Closed Fig. J Pari' BINVENTOR. Gordon Fax BY V UM,

Patented July 10, 1945 SKIP HOIST CONTROL Gordon Fox, Chicago, Ill.,asslgnor to From Engineering Company, Chicago, 111., a corporation ofMaine Application December 11, 1942, Serial No. 488,698

33 Claims.

The present invention relates to improvements in skip hoist controls.

More particularly the present invention relates to improvements in thecontrol method and mechanism for the motors of a skip hoist such as usedin the charging of a blast furnace.

There are advantages in providing two motors for a skip hoist, the twomotors being geared up to winding drum means for controlling the twocables connected to the two skips.

The normal operation of such a system is, of course, a two-motoroperation. According to the present invention the two motors are startedby connecting them initially in series, then in parallel. Furtheracceleration to the full running speed may be accomplished by weakeningthe shunt fields of the motors. As the skips approach the limit oftravel, the speed is reduced by a generally inverse sequence of eventsprior to stopping.

Speaking generally, there are three major steps of operation:

1. Motors in series with forced fields.

2. Motors in parallel.

3. Motors operating with weakened fields.

In blast furnace operation, in accordance with the present invention, anoperator at the stock house normally controls the starting of the skiphoist motors. However, this operator is not given full control of thefunctioning of the motors. According to the present invention the normaloperation of the hoist through its cycle is automatic, the set-up beingprearranged in the hoist house. In general, the operator in the stockhouse acts only to start the hoisting cycle.

There are times, however, when control oi starting and stopping andspeed of the motors should be centered at the hoist house, as forexample when it is necessary to make adjustments or to otherwise servicethe mechanism. Accordingly, the present invention contemplates meanswhereby an operator in the hoist house may assume control over thestarting and stopping of the motors as well as the speed thereof. Thearrangement is such that the operator in the hoist house can operate thehoist with either motor individually. The present disclosure does notmake provision for operating the skip hoist with two motors whencontrolled from the hoist house, for reasons of simplicity, and for thefurther reason that ordinarily operations requiring control at the hoisthouse are carried on only when the hoist is not handling regular loads.

According to the present invention, options are afforded to operate thehoist with either two motors or one motor. This provides for emergencyoperation in the event of failure of either motor or an associatedportion of the control. These options are obtained, so far as the mainmotor circuits are concerned, by means of switches in the main motorcircuits, the shunt field circuits of the motors, and the brakecircuits. Various combinations of main circuits can be obtained byplacing these several switches in their selective positions. Preferablysaid switches are all located in the hoist house.

The present invention contemplates means, re ferred to in thisspecification as a control transfer switch, in the hoist house forprearranging a large number of control circuits for accomplishing aprearranged sequence of events in the operation of the motors, or eitherof them, and their associated parts. According to the illustratedembodiment of the present invention, the control transfer switch hasfive alternative operating positions, which permit the selection of fiveways of operating the control mechanism according to the followingalternatives:

(a) The hoist can be driven by motor No. 1 only, controlled at the hoisthouse.

(1;) The hoist mechanism may be driven by motor No. 1 only, controlledat the stock house.

(c) The hoist mechanism maybe driven by both motors cooperating,controlled at the stock 80 house, i. e... by an'operator at the stockhouse.

(d) The hoist mechanism may be driven by motor No. 2 only, controlledfrom the stock house.

(e) The hoist mechanism may be driven by motor No. 2 only, controlledfrom the hoist house. The control transfer switch must eflect changes-in a multiplicity of control circuits. This is done by combining manysmall switches in a mechanism adapted to change all of the circuitssimultaneously. By positioning this control transfer switch in any oneof the five alternative operating positions, it is possible to eflectfive combinations of a multiplicity of circuits. The positioning of thecontrol transfer switch in any one of the five alternative operativepositions mentioned accomplishes the opening and closing of amultiplicity of small switches in a large number of circuits to causethe rearrangement of these circuits, to accomplish the required sequenceof events in the operation of the motor, or motors, in circuit.

In other words, considering operation in the stock house, if the controltransfer switch is in a position corresponding to alternative (b), (c)or (it) above, combinations of circuits are set up whereby the operatorin the stock house, by the mere pressing of a button or the like, caninstitute a cycle of operations which will follow through automatically.n the other hand, if the control transfer switch is in positioncorresponding to aitemative (a) or (e), according to I which control istransferred to the hoist house,

the operator in the hoist house may start or stop or reverse thecorresponding motor and control thereof by operating a master switch.The controls are such that when the control transfer switch ls inposition corresponding to alternative (41) or (e) the operator in thestock house has no control over the operation of the system (except tostop the hoist in emergency).

Ordinarily, skip hoists are counterbalanced in a substantial degree,since one skip is descending while the other skip ascends. Thedescending skip acts as a counterweight for the ascending skin, so thatit is necessary for the motor to hoist only the net load of material.However, at the time that one skip is started out of the skip pit. theother skip at the top of the furnace is capsized and is in such aposition that its weight is not eifective as a counterweight. At suchtime the motor must develop enough torque to hoist the weight of theskip in the pit plus the weight of the material, plus the weight of thecable, without the assistance of the counterweight effect of the skip atthe top of the hoist. Moreover, there must be some additional torquecapacity in the motor to permit acceleration under these conditions. Thetorque necessary to start and accelerate a normal ore load is likely tobe about 2.5 times the running torque required for such load. a

It is customary to provide skips of sui'iicient volumetric capacities tohandle coke charges of desired weights. It is customary to till theseskips only partially with "ore for the ore charges. In many instancesthe ore charge is of a magnitude of half a skipload. However, it isentirely possible that the skip may be entirely filled with ore on someoccasions, and it is desirable that the hoist be able to handle the skipin such event. The torque required to start a full skipioad of ore outof the skip pit may be as much as three or four times the running torqueassociated with hoisting a normal ore load, and perhaps six or seventimes the running torque required to hoist a coke load. Similarly, it isseveral times the torque corresponding to the root mean square load forthe entire charging cycle.

Since starting torque is the determining factor,

it is logical that the drive should be selected with particularreference to this requirement. Accordingly, in the practice of thepresent invention it is preferred that the hoist have the followin basiccharacteristics. with particular reference to starting torque:

1. Through the use of field forcing and field weakening, in combination,the torque capacity of the motors at low speed is about twice theirtorquecapacity at maximum speed.

2. Since the choice of the gear ratio between the motors and thehoisting drum is determined by the desired running speed, and since thisrunning speed is much above the base speed of the motor. a gear ratio onthe order of 40 to i or 50 to 1 is preferred. As cont asted with theratio usual in prior art, approximately 25 to i, the starting torque atthe winding drum shaft is approximately doubled in relation to a giventorque development at the motor shaft.

An object of the present invention is to p ovide asvaoae an.installation involving skip hoist motors and control mechanism thereforfor automatically obtaining a wide speed range for starting running anddumping, with a minimum use of resistors in the circuits of said motors.

A further object is to provide a drive mechanism and associated controlmechanism for a skip hoist in which the loss of power in resistors isreduced to a minimum.

A further object is to provide a drive mechanism and control mechanismassociated therewith for a blastfurnace skip hoist in which the inherenttorque capacity in the equipment is advantageously proportioned andrelated to the drive requirements.

A further object is to provide a drive mechanism and control mechanismtherefor in a blast furnace skip hoist wherein the running horse powerrequirements and the starting torque requirements are so related thatmotors of minimum size may be employed.

A further object is to provide a drive mechanism and associated controlmechanism for a blast furnace skip hoist employing two motors whereinthe motor. capacities are utilized to the best advantage.

A further object is to provide a drive mechanism and associated controlfor a blast furnace skip hoist in which the demands upon the electricpower supply system are relatively moderate.

A further obiect is to provide an improved drive mechanism andassociated control mechanism for a blast furnace skip hoist employingtwo duplicate motors, wherein the motors have compoundwound motorcharacteristics during one portion of the operating cycle andshunt-wound characteristics during another portion thereof.

A further object is to provide drive mechanism and control therefor foroperation of a skip hoist, in which the speed when dumping a skip willbe uniform and will be independent of the weight of material handled inthe Sk l s.

A further object is to provide drive mechanism and control therefor fora skip hoist, wherein a failure of a coil of a contactor in a motorcircuit will not jeopardize the hoist.

A further object is to provide mechanism for driving and controlling askip hoist, wherein the hoist speed is automatically reduced when thehoist tends to run at a speed in excess of normal.

A further object is to provide mechanism for driving and controlling askip hoist, wherein the hoist speed is automatically reduced when theload exceeds a predetermined amount.

A further object is to provide mechanism for driving and controlling askip hoist, wherein slow-down, as the end of travel is approached, isinsured by an independent check on the operation of the automatic meansprovided to cause such slow-down.

A further object is to provide mechanism for driving and controlling askip hoist employing two duplicate motors wherein either motor may beemployed singly to handle more than half of the rated capacity of thehoist without exceedin the motor size suitable for normal two-motoroperation.

A further object is to provide mechanism for driving and controlling askip hoist employing two duplicate motors, wherein the operating speedwith single motor drive may be substantialiy less than that employedwith normal twomotor drive. 7

A further object is to provide mechanism for driving and controlling askip hoist employing two duplicate motors, wherein the motors may beoperated at relatively high speed and a relatively high gear ratio maybe employed between the motors and the hoist drum.

A further object is to provide mechanism for driving and controlling askip hoist employing two duplicate motors, wherein the division of loadbetween the two motors when operating in parallel at full speed isinsured without prejudice to close speed regulation of the motors whenoperating in series at dumping speeds.

A further object is to provide mechanism for driving and controlling askip hoist employing two niotors, wherein the same armature shuntizmresistors and contactors are employed to meet the differing requirementsof two-motor and/or single-motor operation.

A further object is to provide mechanism for driving and controlling askip hoist employing two duplicate motors which provides for fullautomatic operation of both motors or with either individual motor inresponse to one master means, and provides for control of operation witheither individual motor in response to another master means.

A further object is to provide mechanism for driving and controlling ablast furnace skip hoist which combines reliability and flexibility withsimplicity.

A further object is to provide mechanism for driving and controlling askip hoist which will afford smooth operation.

A further object is to provide a skip hoist drive involving a hoistingdrum and a motor, wherein a brake associated with the motor shaft exertsa rglafigvely powerful effect at the hoisting drum s a A further objectis to provide mechanism for driving and controlling a skip hoist welladapted to meet the needs of commercial operation.

Further objects will appear as the description proceeds.

Referring to the drawings- Figure 1 is a diagrammatic view illustratinga winding drum for operating the two cables of a double skip hoist, saidwinding drum having associated therewith the limit switch, the drivingmotors, brakes and gearing for controlling said winding drum:

Figure 1A is a diagrammatic view illustrating a blast furnace and anincline, skips and a hoist associated therewith;

Figure 1B is a diagrammatic view illustrating in side elevation theassociation of a winding drum and the limit switch, brakes and themotors associated therewith;

Figure 2 is an electrical diagram which for convenience is divided intofive parts, indicated as Figure 2, part A: Figure 2, part B; Figure 2,part C; Figure 2, part D; and Figure 2, part E;

Figure 2, part Al, Figure 2, part B-l, ure 2, part C-l, Figure 2, partD-i, and Figure 2, part E-l, are diagrams explanatory of Figure 2, partA, Figure 2, part B, Figure 2, part C, Figure 2, part D, and Figure 2,part E, respectively; and a Figure 3 is a reference chart indicating theoperation of a control transfer switch constituting part of the presentinvention which figure for convenience is divided into two parts, towitpart A and part B.

Description of instrumentalities As illustrated in Figure 1, a pair ofdriving motors I and 2 is provided. Said motors I and 2 are connectedthrough coupling I and I, respectiveiy, through brakes l and I to gearreduction units 1 and B. The low-speed sides of said gear reductionunits 1 and l are connected, respectively, to pinions 9 and II, whichmesh with the ear II. Said gear II is rigidly secured to the drum II,which has secured thereto the cables l3 and i4. Said cables I! and I4may be connected, respectively, to the right skip and the left skip of ablast furnace charging mechanism. It will be understood that when one orboth of the motors l-2 are energized to cause rotation of the windingdrum I2 in one direction, one of the cables i3 will be wound up upon thedrum l2, and the other of said cables will be paid oil, and, conversely,when the energization of one or both of the motors l-Z is such as tocause reverse rotation of the winding drum I2, the movements of saidcables l3 and I will be reversed. Limit switch means connected to bedriven in synchronism with the drum I! are indicated diagrammatically bythe numeral 15.

Referring to Figure 1A, the numeral l6 indicates a blast furnace and thenumeral I1 indicates a skip incline associated with said blast furnace.Said skip incline is provided with a pair of skips l8 and I9, one ofwhich is illustrated as being in the skip pit Ill and the other of whichis indicated in capsized position for delivering material into thehopper 2| at the top of the blast furnace 18. The skip I8 is shown inposition to receive material from the scale car 22. The cables I! and IIassociated with the winding drum I! are connected to the two skips Illand i9, being trained over sheaves, which need not be described indetail.

A description of the electrical diagram in Figure 2 may be prefaced by astatement of the significance of the numerals and letters used thereon,as follows: I

The numerals H and I2 appearing before upper case letters, as forexample I IOL and IIOL, refer to instrumentalities particularlyassociated with motor No. l.

The numerals ii and 22 appearing before upper case letters, as forexample IIOL and 220L,

refer to instrumentalities particularly associated with motor No. 2.

The letters 00 refer to the operating coil and the contacts responsivethereto of a relay which functions in response to over-current.

The letters 0L refer to the operating coils and the contacts responsivethereto of a relay responsive to overload.

The letters Br refer to one or both of the brakes associated with themotors.

The letter L in general refers to left skip.

The letter It refers in general to the right skip.

The letter A refers in general to accelerating contactors.

The letter P refers in eratlon of the motors.

The letter 8 refers in tion of the motors.

The letters R, as for example Ri-R2, RIO-- RH, refer to resistors eitherin series or shunt relationship with the motor armatures.

The letters AS refer to the operating coil and contacts responsivethereto of armature shunting contactors.

The letters FA refer to the operating coil and contacts responsivethereto of field accelerating relays.

The letters FL refer to the operating coil and contacts responsivethereto or a field loss relay.

general to Parallel opgeneral to series opera- The letters Ff refer tothe transfer switch for the shunt field circuits.

The letters BT refer to the transfer switch for the brake coil circuits.

The letters A-B, B-C, etc., refer to resistors in shunt field circuits,brake circuits, and control or pilot circuits.

The letters UV refer to the operating coil and contacts responsivethereto of an under-voltage or low-voltage relay.

The letters SC refer to the op ratin coil and contacts responsivethereto of a slack cable relay.

The letters 08 refer to the operating coil and contacts responsivethereto of an overspeed relay.

The letters CTS refer to a control transfer switch. This controltransfer switchhas a number of stages identified as CTSI, C'IS2, etc.

The letters RSU refer to the coil and the contacts responsive thereto ofa relay controlling the movement of the right skip up.

The letters LSU refer to the coil and the contacts responsive thereto ofa relay controlling the movement of the left skip up.

The letters RS refer to the contacts of the right skip limit switch.

The letters LS refer to the contacts of the left skip limit switch.

The letters RSU'B refer to a push button control for starting the rightskip up.

The letters LSUB refer to a push button control for starting the leftskip up.

The letter T refers tothe coils and contacts responsive thereto ofvarious timing relays.

The letters SD refer to slow-down, ISD referring to first slow-down, and28D referring to second slow-down.

The letter C refers to conductors.

The letters SN refer to a "slow-down or normal" switch.

The letters MS refer to a master switch.

The diagrams in Figure 2, part A-l, Figure 2, part 3-1, Figure 2, part-1, Figure 2, part 13-1 and Figure 2, part E1, show designations ofelements such as coils, contacts, at cetera, associatedwith the variousinstrumentalities, such as relays, et cetera, the vertical location ofany coil, contact or the like corresponding approximately to thevertical location of this'element in the corresponding part of Figure 2.The broken lines extending downwardly from the character representingeach instrumentality lead to a designation of an element forming part ofthat instrumentality. A full line extending downwardly from adesignation of an element indicates that there are other elementsassociated with that particular instrumentality. If no line extendsdownwardiy from a designation of an element, no further elements areassociated with that particular instrumentality. For example,considering the instrumentality having associated therewith the letters00, it will be noted from Figure 2, art A--1, that this instrumentalityincludes an operating coil 00 located a short distance from the top ofthe diagram represented as Figure 2, part A. The characters 00 do notappear in the diagram Figure 2, part elements of the instrumentality 00appear in Figure 2, part B. Referring now to Figure 2, part 0-1, underthe heading 00, it will be noted that said instrumentality includes thecontacts OCI and the holding coil OCS. Inasmuch as no line extendsdownwardly from the characters 065, there are no other elements embodiedin the instrumentality 00 in the remaining parts of Figural B-l, whichindicates that no The character IL2 indicates the positive main and thecharacter iLl indicates the negative main of a source of constantpotential direct current. Associated with said mains IL2 and im are therunning positive bus RPB (Fig. 2, parts C and D), the series positivebus SPB (Fig. 2, parts C and D), and the negative bus NB (Fig. 2, part0). The character Arm. i indicates the armature of the motor I, and thecharacter Arm. 2 indicates the armature pf the motor 2.

Connected in series with the armature i is a series field windingindicated by the words Stab. Fid. i, meaning stabilizing field.Connected in series with the armature 2 is the series field windin:indicated by the words Stab. Fld. 2, also meaning stabilizing field. Thewords Sh. Fid. I" indicate a shunt field winding associated with thearmature i, and the words "Sh. Fld. 2 indicate the shunt field windingassociated with the armature 2. By means of instrumentalities to bedescribed, the connections to the armature i, armature 2, "Sb. Fld. I,"Sh. Fld. 2, the stabilizing (series) field windings and certainresistors may be controlled to provide the changes of speed and changesin direction of armature rotation required for operation of the skiphoist.

The character IKS indicates a two-bladed sinale-throw knife switch.

The character 2K8 indicates a two-bladed sinale-throw knife switch.

The character 8K8 indicates a two-bladed double-throw knife switch, ofwhich the right-hand blade when in its down position engages anintermediate contact.

The character KS indicates a two-bladed douhie-throw knife switch, ofwhich the right-hand blade'when in its down position engages anintermediate contact.

The character KS (Fig. 2, art B) represents a two-bladed single-throwknife switch in the electric mains.

The character FI'I (Fig. 1, part A) indicates a motor field transferswitch for controlling the connections of Sh. Fld. i and embodies adouble-pole double-throw knife switch.

The character FI2 (Fig. 1. part A) indicates a motor field transferswitch for controlling "Sh. Fid. 2" and embodies a double-poledouble-throw knife switch.

when Fri and PM are closed upwardly they connect "8h. Fld. I and "Sh.Fld. 2" in series. when one or the other of said switches is closeddownwardly. its corresponding shunt field winding is cut out of circuitand a resistor (to be referred to presently) is cut into circuit.

Character BTI indicates a brake transfer switch for brake I, embodying adouble-pole doublethrow knife switch.

The character BT2 indicates a brake transfer switch for brake 6embodyins a double-pole double-throw knife switch.

The character 00 (Fig. 2, part A) represents the series coil of a relay,the contacts or which are designated OCI (Fig. 2, part c). This samerelay has a shunt coil 068 (Fig. 2, art c). The series coil 00 functionsto close contacts OCI in case of excessive load on the hoist. The shuntcoil 008 then functions to hold contacts 00! closed after the current inseries coil 06 has diminished to below a predetermined value. The urposeof the relay embodying the coil 00 is to cause the speed of the hoist tobe decreased below full runnina speed in the event of anexcessive load.This is.done through closure ofthe relay contacts QFAI (Fig. 2, part A)in response to the coil WA (Fig. 2, part which is controlled by thecontacts OCI.

llOL, CL, CL and IIOL ar series coils of overload relays (Fig. 2, partA). The contacts of these relays are designated, respectively, IIOLi,tlOLl, 2201.! and IIOLl (Fig. 2, part B). All these contacts are biasedto closed position and are connected in circuit with the coil UV (Fig.2, part B), which forms part 01' an undervoitage relay. to be referredto presently.

The characters Br and 2IBr (Fig. 2, part A) are the series coils ofseries brake relays having, respectively. the contacts l-lBri and IIBrI(Fig. 2, part C), which contacts are biased to open position and areclosed when current flows in coils (lBr and IIBr. Closure of saidcontacts liBrl and 2181'! results in the energizing of coils (Br and2131 or the brake relays, which have the flmction of releasing thebrakes and 8. The series brake relays embodying the coils H81 and 2031-have the function of preventing release of the brakes 5 and 6 untilafter suflicient current flows in the armature circuits of the motors land 2 to develop torque of sullicient magnitude to insure saiety whenthe brakes are released.

Contacts IiLl, IZLI, HR! and "RI, and similarly IILl, 2211i, ZIRI and"Rf (Fig. 2, art A) are the main contacts of directional contactorsresponsive. respectively, to the coils HL, (211-, HR, (2R, 21L, 22L, HRand HR (Fig. 2, part B). These contactors function to determine thedirection of flow of current in armatures I and 2, thereby determiningthe direction or movement of the hoist. The directional contactorshaving coils IIL, I21), UL and 221. are provided, resnuectively, withauxiliary contacts L2, 2IL2, IlRiand MR2 (Fig. 2, part B), thefunctioning of which will be explained presently.

Contacts Al, IZAI and similarly Al and. A! (Fig. 2, north) are the maincontacts of accelerating contactors responsive, respectively, to thecoils HA, HA, ZIA and 22A (Fig. 2, part D). These contactors function,respectively. to cut into and out of circuit resistors (RI-IE2, (R2-(R3, IRA-2R2 and 2122-2111, which may be designated as parallelaccelerating resistors (Fig. 2-, part A) These contactors haveadditional amniiary contacts HA3 (Fig. 2, part C), HA4 (Fig. 2, part D),((A5'(Fig. 2, part D), "A! (Fig. 2, part C), HA4 (Fig. 2, part 0), ZIAZ(Fig. 2, part C), A! (Fig. 2, part 0), 21A! (Fig. 2, part D), 22A! (Fig.2, part C) and HA5 (Fig. 2, part D). of these contacts, HA3. HA5, (2A8,HA4, HA2, HA3, 22A: and HA5 are biased to closed position and are openwhen their corresponding coils are energlzed, and contacts HM and HA4are biased to open position and are closed when their correspondingcoils are energized.

Contactors PI and "PI (Fig. 2, part A), both biased to open position,are responsive to coils HP and MP respectively (Fig. 2, part C). Thesecontactors function to connect the armatures i and 2 in parallel acrossthe mains. Bald coil HP also controls additional contacts UPI (Fig. 2,part B), biased to closed position, UB3 (Fig. 2, part C), biased toclosed position, llPl (Big. 2. part C), biase d to open position, andIIPS '(lilg. 2, .part C), biased to open-position. Contactor collJlPalso controls contacts-HP! (Fig. 2, part B), biased to closed posltion-llPj (Eig ll, h'g sfil lassd c lqsedimt o h sighs- 2, o:blasetistoeoperi' positione This contactcr Sl functions to connectarmatuies I and 2 in series. This contaotor has addition contacts 32 and83, both biased to closed position, and Bl and S5, both biased to openpodtlon. Contacts 82, S3 and B8 are shown in Figure 2, part 0, andcontact SI is shown in Figure 2, P t D. Contactors IA! and 2A1 (Fig. 2,part A), both biased to open position, respond to the coils IA and 2!.(Fig. 2, part 0). These contactors function to control seriesaccelerathig resistors Rl-R2 and R.2 -R3 (Fig. 2, part A). Saidcontactors IA! and (A2 have additional contacts 2A}, biased to closedposition, 2A3, biased to closed position, and 2A4, biased to openposition (all as shown in Fla. 2. part 0). The function oi theseauxiliary contacts will appear presently.

Contactors IASI and 2A5! (Fig. 2. part A), both biased to open position,are responsive to coils IAS and 2A5 (Fla. 2, part D). These contactorsfunction, respectively, to connect resistors RIO-RH and RiI-Rlt-Rll intoarmature shunting relationship with armatures I and 2 to): two-motoroperation. When operating with a single motor both or these contactors(AS! and ZASI function to connect the aforementioned resistors intoarinature shunting relationship with whichever amisture is selected foroperation. These contactors have additional contacts (A83 (Fig.2, partB), biased to open position, and- IASI (Fig, 2, part D), biased to openposition.

Coll FL (Fig. 2, part A) is connected in series with the shunt fields ofthe motors I and 2. Said coll controls the contact BLl (Fig. 2, part B),biased to open position. This contact FLl, together with a. number ofother contacts, t be reterredto presently, is in circuit with the coilUV of an under-voltage relay (Fig. 2, part B), to be reierred topresently.

The/"relay contacts (PM, 2PM and (WM, all biased to open position (Fig.2, part A), are responsive. respectivehr, tocoils (FA, HM. and IEA (Fig.2, part C). These relay contacts function to control resistors O- -D,D-E and F-G, all connected in circuit to the shunt field wlndinzs ot themotors i and 2 and control the strength 01' the motor fields. Coll IFAalso controls the auxiliary contact IFAI (Fig. 2, part D), biased toopen position. Coil IFA also controls auxiliary contacts IPA! (Fig. 2,part E), biased to open position, and ZFAS (Fig. 2, part B), biased toopen position. Coil 3FA also controls the auxiliary contacts :iF'AZ(Fig. 2, part B), biased to open position, and IF'Al (Fig. 2. part C),biased to open position.

Resistors H-I and J--L are resistors which by manipulation oi the knifeswitches F'll and FTI (Fig. 2, part A), may be substituted for the shuntfields ol. motor i and motor), respectively.

Relay contacts iBri and 2Bri (Fig. 2, part A), both biased to openposition, are responsive, respectively, to cells 181' and 2Br (Fig. 2,part C). These are shunt relays which control the introduction ofcurrent into the operating solenolds BC! and B05 of brake i and brake 6.Brake relay iBr hasadditional contacts I Bg'Z and [Br-l (Fig-2, part C),both biasedto openposition,

" a'nd' lBrl'(Fi3. 2, part'E), biased-ioqclosedposiii ih 52 33 a willBC! oi brake O by manipulating the switches associated with saidsolenoids. This is done when it is desired to remove one or the other ofthe brakes from service temporarily, continuing with the remaining brakein service.

The under-voltage relay, thecoil or which is designated by the characterUV and the contacts oi which are designated by the character UVi, isshown lnFigure 2, part B. This relay iunctions to protect the hoist incase failure of voltage. It also responds to various safety devices suchas overload relays liOL, i201, H01.- and 1201., which have theircorresponding contacts IIOLi, ilOLl, IIOLI and OM located in series withsaid underwoltage relay coil UV. Bald coil UV also responds to loss ofthe shunt neld, resulting in the opening of the contacts FLI, responsivein turn to the hold loss coil FL (Fla. 2, part A). It also responds tothe openin: oi the slack cable switch SCI, which throughinstrumentalities well known to those skilled in the art is caused toopen in case either cable at the hoist becomes slack. The under-voltagecoil UV also responds to the switch OSi, biased to closed posltlon,which may be responsive to an over-speed device, which, if preferred,may be controlled by a fly ball governor. Devices for purpose are wellknown to those skilled in the art. It may be explained that in case thehoist attains excessive speeds, the switch 08! will be openedmechanically. The under-voltage coil UV also responds to a combinationoi contacts arranged to protect the hoist in case it fails to slow downwhen it approaches the limit of its travel. These contacts are embodiedin the members RBUI, biased to closed position and responlive to a coilRBU, to be described presently; L80 responsive to a limit switch, to bedescribed presently; RSI responsive to a limit switch, to be describedpresently; LSUI, biased to closed poaitioIL responsive to the coil ISU,to be described presently; IIPZ and MP2, both biased to closed positionsand responsive respectively to coils HP and 22? (Fig. 2, part C), to bedescribed presently; contacts IFAI, biased to open,

position and responsive to coil SFA (Fig. 2, part C), to be describedpresently; contacts 131'), biased to closed position and responsive tocoil IBr (Fig. 2, Part C), to be described presently; stage C'ISl, to bedescribed presently; contacts 21'' biased to open position andresponsive to call iFA (Fig. 2, part C), to be described presently; andthe contacts IAS3. biased to open position and responsive to coil [AB(Fig. 2, part D).

The words "Stop Reset-Run" indicate a push button of the walking beamtype (Fig. 2. part B). This push button functions to stop the hoist incase or emergency and to reset the under-voltage relay alter a voltage{allure or after an emergency stop. The operator, in the event of anemergency, may stop the hoist by depressing the Stop Reset" side oi thwalking beam. thereby opening the switch WI.- and opening the circuit orthe coils IIL, IIL, IIL, 22L, HR, HR, HR and "R. Said "Stop Reset-Runbutton will remain in the position to which it is moved by the operator.Depressing oi the "Stop Reset" button re cults in the closing or switchUVU (Fig. 2. part B). Depressing or the "Run" button of the walking beamwill open the switch UVU and will close the switch UVL.

The circuit diagram in Figure 2 includes a number of stages or switchesbearing the letters C'lB, iollowed by a numeral. These switches are allpart 0! a control transfer switch 6'18.

This control transfer switch CTS is preferably located in the hoisthouse and has the function of prearranging a large number of circuitsior accomplishing a prearranged sequence of events in the operation 01'the motors i and 2, or either 01 them, and their associated parts.According to the illustrated embodiment of the present invention, thecontrol transier switch CTB has live alternative operative positions,which permit the selection of five ways for operating the hoistmechanism, as follows:

(a) The hoist can be driven by motor No. 1 only, controlled from thehoist house.

(12) The hoist mechanism may be driven by motor No. i only, controlledfrom the stock house.

(c) The hoist mechanism may be driven by both motors. controlled fromthe stock house.

(11) The hoist mechanism may be driven by motor No. 2 only, controlledfrom the stock house.

(e) The hoist mechanism may be driven by niotor No. 2 only, controlledfrom the hoist house.

The control transfer switch must eflect changes in a multiplicity ofcontrol circuits. This is dona by combining many small switches in amechanism adapted to change all of the circuits simultaneously. Bypositioning this control transfer switch in any one of five operatingpositions. it is possible to effect five combinations of a multiplicityof circuits. The motioning oi the control transfer switch in any one o!the five alternative operating positions mentioned accomplishes theopening and closing of a multiplicity of switches in a large number ofcircuits to cause the rearrangement of these circuits to accomplish thedesired sequence of events in the operation of the motor or motors.

In other words, considering operation from the stock house, if thecontrol transfer switch is in a. position corresponding to (b), (c) or(d) above, combinations of circuits are set up whereby the operator inthe stock house; by mere pressing of the 15013 or RSUB button (Fig. 2,part B), can institute a cycle oi operations which will follow throughautomatically. On the other hand, if the control transfer switch is in aposition corresponding to (a) or (e), according to which controlistransferred to the hoist house. the operator in the hoist house maystart or stop the corresponding motor by operating a master switch,which master switch is indicated diagrammatically in Figure 2, part D,to be described presently. The controls are such that when the controltransfer switch is in a position corresponding to (a) or (e), theoperator in the stock house has no control over the operation of thesystem except to stop the hoist in emergency, which he can do bydepressing the "Stop Reset" button (Fix. 2. part B).

Control transfer switches suitable for the pub D se above described arewell known to those skilled in the art and need not be described indetail. It will be suliicient to state that the switches or stages whichare embodied in the control transier switch CTS involve contactsindicated by the letters ofl-b and bc. By reference to the chartappearing in Figure 3 it will be noted that switches or stages areinvolved having the numerals 1, 3, 4, 5, 6, 'l, B, 9. l0, l1, l2, 13,14,15, l6, i7, 19, 20, 2i, 22, 23, 24, 25, 26, 27, 2B and 29. Xsignifies that the corresponding switch or stage is closed and a dashindicates that the corresponding switch or stage is open at the contacts-1: or b-o. For example, referring to the stage CTSI, by reference tothe chart Figure 3. it will be noted that if the control switch CTS ismoved to one of its live alternative positions such that the control ofmotor No. 1 is to be had from the hoist house, the contacts o-b areclosed and contacts b--c are open. If control of motor N0. 1 is to behad from the stock house, the control transfer switch would be moved tothe second of its live alternatlve positions, in which position thecontacts ob would be open and the contacts bc would be closed. In theevent that two-motor control from the stock house is desired, controltransfer switch would be thrown to the third of its five alternativepositions, and contacts ob would be open and the contacts b-c would beclosed. If control of motor No. 2 is desired from the stock house, thecontrol transfer switch would be thrown to th iourth of its livealternative positions, in which case contacts c-b of stage C'ISl wouldbe open and contacts b--c would be closed. Finally, ii control of motorNo. 2 is to be had from the hoist house, the control transfer switch CTSwould be moved to the fifth of its five alternative positions, in whichcase the contacts 11-!) 0i CISl would be closed and the contacts bcwould be open.

Contacts LSUI and RSUI (Fig. 2, part B), both biased to closed position,are responsive to the coils LSU and RBU (Fig. 2, part B). These arecomponent parts of directional relays which respond to push buttons LSUBand RSUB, which determine the direction of movement of the hoist. Theserelays have a number of other contacts, to wit, LSU! and RSUI (Fig. 2,part B), and LSU3, LSU. RSU! and RSUl (Fig. 2, part D). Said pushbuttons IBUB and RSUB are located at the two ends or a walking. beam,and when the push button ISUB is depressed. it closes switch LSUBI andopens switch RSUBI Conversely, when the push button RSUB is depressed.it opens switch LSUBI and closes switch RBUBI.

The characters LS and RSI indicate contacts responsive to a limitswitch, to be described presently.

The character lT indicates the count a time relay (Fig. 2, part 0). Saidcoil controls the contacts lTl and (T2, both biased to closed positions,and functions to introduce a time delay in the energlzation of the coilsIA and 2A to control the acceleration of the motors l and 2 when theirarmatures are connected in series. Said coils IA and IA control thecontacts (Al and MM, respectively (Fig. 2, part A), both biased to openposition.

21 designates a coil ot a timing relay (Fig. 2, part 0). This coilcontrols contacts Z'Il and IT! (Fig. 2, part D), both biased to closedposition. Said contacts function to control the energization oi coilsHA, 2IA, IZA and 22A, which in turn control the contacts llAl, IIAI,IIAI and Hill (Fig. 2, part A), whichcontrol the series acceleratingresistors in the circuits of the two armatures I and 2 connected inparallel.

3T designates the coil of a timing relay having the contacts 31! and3T1, biased to open position (Fig. 2, part 0). v I trol the time ofenergization of rela'yjcoils 21% and SFA, which in turn control therelay'contacts lFAl and IFAI (Fig. 2, part A), which control thestrength'ol the shunt fields of the motors l and 2. l

T (top or partD oi Fig. 2) designates the coil This relay functions" tocol.' l'

01 a timing relay having the contacts l'rl (Fig. 2, part 0), biased toclosed ,position. Contacts 4'I'i, by their closure. cause energinationoi the series contactor coil 8, thereby initiating a transier trom theparallel connection to the series connection at the time or slow-down.The timing relay having the coil QT introduces a time element to delaythis transter by a desired time interval after the opening of contactsi805 (Fig. 2, part D), later discussed.

ISD designates a coil of a "first slow-down" relay. This coil is shownin Figure 2, part D. The relay has a number of contacts, to wit, ISDB.biased to open position, ISDI, biased to closed position, [8132, biasedto closed position, ISD3. biased to closed position, all appearing inFigure 2, part C, and lSDS, biased to open position (Fig. 2, part D),and lSDS, biased to open position (Fig. 2, part D), and iBDl, biased toclosed position, appearing in Figure 2, part D. Said coil (Fig. 2, partD) is energized when the running positive bus RPB is energized at thetime that the hoist was started by depressing the button RSUB. At thistime the contacts RS2 in circuit with the coil ISD are bridged by thesegment R8! of a limit switch to be described presently, However, coil16D is deenerglzed when the hoist reaches its "first slow-down" point,as determined by said limit switch, due to the fact that said contactsRS2 will be unbridged by the limit switch segment RS2. Deenerglzation ofthe coil ISD results in the strengthening of the shunt fields oi themotors, and subsequently it causes transfer from parallel to seriesconnection or the motors. The mode or operation for accomplishing thesechanges will be described under the heading Mode of operation."

ZSD designates the coil of a second slowdown" relay. This coil is shownin Figure 2-, part D. This relay has contacts ZSDI, biased to openposition, and ISDZ, biased to closed positlon (Fig. 2, part C), and2SD3, biased to open position (Fig. 2, part D). This relay functions toenergize the coil IFA when the beast ap proaches the end of travel. Itscircuit is from main [L2 through ontacts S4, contacts ISDI. contacts b-coi C'ISll, through coil IFA to negative main lLl. Energization or thecoil (FA causes the closure of the contacts IF'AI (Fig. 2, part A)short-clrcuitlng the resistor CD, forcing the shunt fields and furtherslowing down the speed 0! the motors. As applied to single-motoroperation, this relay tunctions through the contacts ISD! to energizethe coil 2A8 (Fig. 2, part D), causing the closure of the contacts IASI(Fig. 2, part A) thereby shunting the armature oi said motor to reducethe speed thereof.

A walking beam type push button designated as slow-normal" is shown inFigure 2, part D,

in series with the coil ISD. If the "Slow" button is depressed. coll ISDcannot be energized.

The first low-down" relay therefore does not which means that (he leftskip ismoving down wardly. Said limit switch moves to the leit when theright skip is moving downwardly. which means that the left skip ismoving upwardly. Said limit switch is provided with segments LS4. RS4,LS5, RS5, ISL RSI, L52, B82, LS3, RS3, LS1, RS1, L58 and RSI. Each oithese segments is adapted to bridge or unbridge a similarly designatedpair of contacts located opposite thereto in the various portions oiFigure 2. For example, contacts LSI (Fig. 2, part B) are closed whenthese contacm' are bridged by the corresponding segments 154.

When the hoist starts to hoist the left slrip, contacts LSI are bridgedby the extreme left portion of the segment LS1. As the left skipascends, segment LS4 may be considered as moving toward the leit overthe contacts LS4. When the lefthand skip has ascended to a pointapproaching its limit oi travel, contacts LS4 are no longer bridged bythe segment LS. Similarly, contacts RSl are ,brldged by the right-handportion of the segment RSO when the right skip starts to ascend. SegmentRS4 departs from a bridging relationship with contacts RS4 when theright skip approaches its limit of travel.

The lengths of the various segments are so chosen as to govern theparticular points in the skip travel at which the various actions are tooccur. For instance, segment LS cooperates with contacts LS5 to causethe hoist to be stopped by deenergizing the coil LSU when the leit skipreaches the extreme limit 0! upward travel.

Under usual operation, the control responds to push buttons LSUB andRSUB, previously described (Fig. 2, part B). At times, however, it isdesired to control the movements of the skip hoist at the hoist house.This is done, for example, when cables are to be adjusted, etc, For thispurpose the master switch MS (Fig. 2, part E) is provided at the hoisthouse. This master switch MS is conventionally shown in diagrammaticform. It is an article of commerce and need not be described in detail.It may be stated briefly that the particular master switch MS iorcooperation with the remaining elements of the system will have an "off"position and, as illustrated, has six positions to the right fordetermining six diflferent speeds of upward movement oi the right skipand six positions to the leit ior determining six diiierent speeds ofupward movement oi the left skip. Master switches are readily availablehaving any number 01' positions within a wide range. The master switchMS has nine stages, as indicated. The topmost oi these nine stagescontrols the switch MSI. When the master switch is in its "oil"position, said switch MS! is closed. when said master switch is at an?oi its six illustrated positions to the right or any of its sixillustrated positions to the leit, the switch MS! is closed, asindicated by the X: marking the intersection oi the line representinilstage 2 with the particular position or point oi the master switch.

With respect to stage 3, the switch M83 is closed when the master switchis in its oil position and is closed when said master switch is in thefirst, second or third position to the ight or to the leit, but is openwhen the master switch is in the fourth, filth or sixth position to theright or to the left.

With respect to stage I, the switch MS is open when the master switch isin the "of!" position. is closed when the master switch is in any one ofthe six illustrated positions to the leit, and is open when the masterswitch is in any one or the six illustrated positions to the right.

With respect to stage 5, the switch M is open when the master switch isin the "on" position and is also open when the master switch is in anyone of its six illustrated positions to the left, but is closed when themaster switch is in any one of the six illustrated positions to theright.

With respect to stage 5, the switch MSG is open when the master switchMS is in the "of!" position, is closed when the master switch is in thefirst, second, third or fourth position either to the right or left, andopen when the master switch is in the fifth or sixth position to theright or left.

with respect to stage i, the switch MS! is open when the master switchis in "oil?" positlon, is closedwhen the master switch is in the first,second, third. fourth, or fifth position to the right or left, and isopen when the master switch is in the sixth position to-the right orleft.

With. respect to stage 8, the switch MB! is open when the master switchMS is in "o position, is closed when ,the master switch is in the firstor-- second position to the right or left, and is open whensaid masterswitch is in the third, fourth, filth, or sixth position to the right orleft.

With respect to stage 9, the switch M89 is open when the master switchis in "01!" position, is closed when the master switch is in the firstposition either to the left or right, and is open when the master switchis in the second, third, fourth, fifth, or sixth position to the left orright.

By reason. of the master switch M8, the operator may ontrol the speed ofascent or either skip by choosing any one oi the six illustratedpositions to the right or left, depending upon which skip he desires tohave ascend. The first positlon in either direction gives a minimumspeed. The second position gives the next higher speed.

etc, until the sixth point is reached, at which point the maximum speedof operation results. This speed of operation is controlled by thereloss and contactors responding to the position of the control transierswitch CTS. As will be explained presently, other positions, such as aseventh position (or upward movement oi each skip, may be utilized forfurther refinements or control.

Various conductors have been shown, indicated by the characters CG, Cl,01, C3, Cl, 06, CS, Cl, CI, C0, etc. These conductors have been brokenaway to avoid the multiplicity of lines, but their connections will beperfectly clear from the diagram.

Mode of operation The detailed description oi the mode of operation oithe above described instrumentalities will be prefaced by a briefoutline of the mode oi operation, omitting intermediate steps. Thisbrie! outline will be iollowed by a more complete descrlption.

Referring first to normal two-motor operation, and assuming that theright-hand skip is in the pit, the operator will depress the buttonRSUB, resulting in the closure'oi the contactor SI connecting thearmatures i and I in series. The resistors Rl-Rl and lib-R3 are in thisseries circuit. The relays connected across the resistors C-D, FG and DEare open while the motors are at rest and while the starting operationis initiated.

